The present invention relates to a method of retarding sand build up in heavy oil wells.
In some geographical areas, heavy oil can be extracted from underground formations using rotary pumping apparatus. One such geographical area is the region around Lloydminister, Alberta, Canada. It has been found, however, that the sand content in the wells around Lloydminster is causing frequent and costly servicing problems. The rotary pumping apparatus used is incapable of carrying the sand to surface. This is due, in part, to a restriction in flow which results from rod couplings positioned at intervals of approximately 7.5 meters extending up the well. As a result, sand settles toward the bottom of the wells. Approximately, once a month the wells become clogged with sand to the point that they will no longer produce oil. When this occurs a service rig must be sent out to clean out accumulated sand.
What is required is a method of retarding sand build up in heavy oil wells, as a substantial saving can be realized in reduced servicing costs and increased production if the time interval between servicing can be lengthened.
According to the present invention there is provided a method of retarding sand build up in heavy oil wells. A first step involves providing a pumping apparatus with subterranean impellers coupled to a rotary top drive unit by a plurality of connective rods. The plurality of connective rods have fixed outwardly extending vanes that rotate with the plurality of connective rods and are configured to provide a supplementary lifting force. A second step involves positioning the plurality of connective rods in a heavy oil well having a circumferential sidewall. A third step involves activating the rotary drive unit to rotate the plurality of connective rods. The vanes attached to the connective rods assist in lifting sand to surface with the heavy oil.
The method, as described above, greatly reduces the rate at which sand settles in the heavy oil well. The vanes can be configured in a number of different ways to provide a supplementary lifting force. Beneficial results have been obtained through the use of helical vanes. It is preferable that the vanes do not engage the circumferential sidewall of the well tubing as this would create unnecessary drag upon the rotation of the connective rods. It is, therefore, recommended that an annular clearance space be provided between an outer edge of the vanes and the circumferential sidewall of the well tubing.